Maintaining frequency layers in parallel during cell reselection

Abstract

A UE and method for performing cell selection / reselection on a radio frequency associated with a network slice are disclosed. One UE (400) includes a processor (405) and a transceiver (425) that camps (610) on a first frequency layer of a RAN (120) while in an RRC idle state, the first frequency layer (310) supporting a first set of network slices (311), wherein the first set of network slices (311) is prioritized for use with a first frequency. The processor (405) iteratively performs (615) a cell search on a second frequency layer (320) while the device is camped on the first frequency layer, the second frequency layer (320) supporting a second set of network slices (321), wherein the second set of network slices (321) is prioritized for use with a second frequency. The processor (405) concurrently maintains (620) the second frequency layer (320) while in the RRC idle state.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 028,510, titled “NETWORK-ASSISTED OPTIMAL SLICE SELECTION IN 5G SYSTEM,” and filed on May 21, 2020, by Prateek Basu Mallick, Ravi Kuchibhotla, Joachim Loehr, Hyung-Nam Choi, and Genadi Velev, which is incorporated herein by reference. This application also claims priority to U.S. Provisional Patent Application No. 63 / 028,511, titled “UE-BASED OPTIMAL SLICE SELECTION IN 5G SYSTEM,” and filed on May 21, 2020, by Prateek Basu Mallick, Ravi Kuchibhotla, Joachim Loehr, Genadi Velev, and Hyung-Nam Choi, which is incorporated herein by reference. TECHNICAL FIELD

[0003] The subject matter disclosed herein relates generally to wireless communication, and more particularly, to performing cell selection / reselection on a radio frequency associated with a network slice. BACKGROUND

[0004] In certain wireless communication systems, a network operator can prefer a user equipment (“UE”) to camp on a cell on a first carrier providing coverage, but to establish a radio resource control (“RRC”) connection on a different cell on a second carrier supporting a slice ‘x’ (alternatively, supporting a service ‘x’) with minimum delay once an upper layer initiates a service request procedure for slice / service ‘x’. However, monitoring separate radio carriers increases power consumption at the UE. SUMMARY

[0005] Procedures for performing cell selection / reselection on a radio frequency associated with a network slice are disclosed. The procedures can be implemented by an apparatus, a system, a method, or a computer program product.

[0006] One method of a user equipment ("UE") device includes configuring the UE to use a first set of network slices and a second set of network slices and camp on a first frequency layer of a radio access network ("RAN") while in a radio resource control ("RRC") idle state, the first frequency layer supporting the first set of network slices, wherein the first set of network slices is prioritized for use with a first frequency. The first method includes iteratively performing a cell search on a second frequency layer while the UE is camped on the first frequency layer, the second frequency layer supporting the second set of network slices, wherein the second set of network slices is prioritized for use with a second frequency. The first method includes maintaining the second frequency layer in parallel while in the RRC idle state by performing a cell reselection on the second frequency.

[0007] Another method of a UE includes receiving a broadcast message including a persistence check value for a first cell and generating a random value during a cell reselection procedure. The second method includes comparing the generated random value to the persistence check value and selectively stopping the cell reselection based on a result of the comparison. BRIEF DESCRIPTION OF DRAWINGS

[0008] More particular description of the embodiments briefly described above will be rendered by reference to specific embodiments, which are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0009] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for performing cell selection / reselection on a radio frequency associated with a network slice;

[0010] Figure 2 is a block diagram illustrating one embodiment of a 5G New Radio ("NR") protocol stack;

[0011] Figure 3 is a diagram illustrating one embodiment of a RAN deployment;

[0012] Figure 4 is a diagram illustrating one embodiment of a user equipment device that can be used to perform cell selection / reselection on a radio frequency associated with a network slice;

[0013] Figure 5 is a diagram illustrating one embodiment of a network device that can be used to perform cell selection / reselection on a radio frequency associated with a network slice;

[0014] Figure 6 is a flow diagram illustrating one embodiment of a first method for parallel maintenance of a second frequency layer; and

[0015] Figure 7 is a flowchart illustrating one embodiment of a first method for cell reselection using a persistent check value. DETAILED DESCRIPTION

[0016] Those of skill in the art would understand that aspects of the embodiments can be embodied as a system, method or program product. Accordingly, aspects of the embodiments can take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects that can all generally be referred to herein as a "circuit," "module" or "system." Furthermore, aspects of the embodiments can take the form of program product embodied in one or more computer readable storage media having computer readable program code embodied thereon.

[0017] By way of example, the disclosed embodiments can be implemented in hardware circuitry (including custom ultra- large-scale integration ("VLSI") circuitry or gate arrays), off-the-shelf semiconductors (such as logic chips, transistors or other discrete components). The disclosed embodiments can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. As another example, the disclosed embodiments can include one or more physical or logical blocks of executable code, which may, for example, be organized as an object, procedure or function.

[0018] Furthermore, embodiments can take the form of a program product embodied in one or more computer readable storage media having computer readable program code embodied thereon. The storage media can be tangible, non-transitory and / or non-transmission. The storage media can not embody signals. In a particular embodiment, the storage media only takes the form of a signal in accessing the code.

[0019] Any combination of one or more computer readable medium can be utilized. The computer readable medium can be a computer readable storage medium. The computer readable storage medium can be a storage device storing the code. The storage device can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0020] More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ("RAM"), a read-only memory ("ROM"), an erasable programmable read-only memory ("EPROM" or Flash memory), a portable compact disc read-only memory ("CD-ROM"), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0021] The code used to implement the operations of the embodiments may be written in any number of lines and may include one or more of the following programming languages: object-oriented programming languages ​​(e.g., Python, Ruby, Java, Smalltalk, C++, or similar), conventional procedural programming languages ​​(e.g., the "C" programming language or similar), and / or machine languages ​​(e.g., assembly language). The code may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer via any type of network, including local area networks ("LANs"), wireless LANs ("WLANs"), or wide area networks ("WANs"), or may be connected to an external computer (e.g., via the Internet through an Internet service provider ("ISP").

[0022] Furthermore, the features, structures, or characteristics described in the embodiments can be combined in any suitable manner. In the following description, numerous specific details are provided to provide a thorough understanding of the embodiments, such as examples of programming, software modules, user selection, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc. However, those skilled in the art will recognize that the embodiments can be practiced without one or more of the specific details or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail so as not to obscure aspects of the embodiments.

[0023] Throughout this specification, references to "an embodiment," "embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Therefore, unless expressly specified otherwise, the phrases "in an embodiment," "in an embodiment," and similar language appearing throughout this specification may (but not necessarily) refer to the same embodiment, but rather mean "one or more, but not all, embodiments." Unless expressly specified otherwise, the terms "comprising," "including," "having," and variations thereof mean "comprising (but not limited to)." Unless expressly specified otherwise, the list of items does not imply that any or all items are mutually exclusive. Unless expressly specified otherwise, the terms "a" and "described" also refer to "one or more."

[0024] As used herein, a list with “and / or” conjunction includes any single item in the list or a combination of items in the list. For example, a list of A, B and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term “one or more of’ includes any single item in the list or a combination of items in the list. For example, one or more of A, B and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term “one of’ includes one and only one of any single item in the list. For example, “one of A, B, and C” includes only A, only B, and only C and excludes combinations of A, B, and C. As used herein, “a member selected from the group consisting of A, B, and C” includes one and only one of A, B, or C and excludes combinations of A, B, and C. As used herein, “a member selected from the group consisting of A, B, and C and combinations thereof’ includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C.

[0025] Aspects of the embodiments are described below with reference to schematic flowcharts and / or schematic block diagrams of methods, apparatus, systems, and program products according to the embodiments. It will be understood that each block of the schematic flowchart and / or schematic block diagrams, and combinations of blocks in the schematic flowchart and / or schematic block diagrams, can be implemented by code. The code can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0026] The code can also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0027] The code can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0028] The diagrams in the figures illustrated possible architectural, functional, and operational aspects of devices, systems, methods, and program products according to various embodiments. In this regard, each block in the flowcharts and / or block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending on the functionality involved. Other steps and methods can be conceived that are equivalent in function, logic, or effect to those illustrated, with the scope of the present disclosure intended to include all such steps and methods.

[0029] It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession can in fact be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods can be conceived that are equivalent in function, logic, or effect to those illustrated, with the scope of the present disclosure intended to include all such steps and methods.

[0030] Although various arrow types and line types can be employed in the flowcharts and / or block diagrams, they are merely meant as an aid to better understand the present embodiments. One having ordinary skill in the art will understand that some of the arrows, or other connective notation can be used to indicate a waiting or monitoring period of time between enumerated steps of the depicted embodiments. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations thereof, can be implemented by special purpose hardware-based systems which perform the specified functions or actions, or combinations of special purpose hardware and code.

[0031] The description of elements in each figure can refer to elements in a previous figure. Like numbers refer to like elements throughout the several figures, including like elements of alternative embodiments.

[0032] Generally, the present disclosure describes systems, methods, and devices for performing cell selection / reselection on a radio frequency associated with a network slice. A mobile communication network operator can prefer a user equipment (“UE”) camp on a cell on a carrier ‘fl’ providing coverage, but once an upper layer initiates a service request procedure for a slice / service ‘x’ to establish an RRC connection on a different cell on a carrier ‘f2’ supporting the slice / service ‘x’ with minimal delay. From a UE perspective, it would be necessary to minimize power consumption during the above procedure while ensuring optimal user experience.

[0033] In some embodiments, the UE receives a list of frequencies for each of the slices in a list of allowed slices upon successful registration to the network and / or the UE receives a list of supported frequencies for each of the slices in a list of rejected slices upon successful (or otherwise) registration to the network. Note that the frequency of a network slice can be in a radio frequency band (i.e., a defined frequency range) different from the radio frequency band of the serving cell. Thus, as used herein, a “frequency of a network slice” refers to a frequency / band combination (e.g., as defined in 3GPP TS 38.104). In certain embodiments, the radio frequency band can be implied. In other embodiments, the radio frequency band can be explicitly indicated.

[0034] However, a UE in'mode d' operation (as described in 3GPP TS 23.501, chapter 5.15.9) can not contain the NSSAI (slice information) when starting the registration procedure. In addition, the above embodiments do not help for the initial cell selection case when the UE has not been registered in the current network. Furthermore, the above embodiments do not work if the network does not provide the slice / frequency mapping as a result (i.e. output) of the registration procedure.

[0035] In addition to the above disadvantages, if the slice / frequency mapping (provided during the registration procedure) is not homogeneous across the registration area (i.e. the list of tracking areas ("TA") signaled to the UE), the UE cannot determine whether it can still find the supported slice on the indicated frequency after moving to other parts of the provided TA list. Here, the registration area can be indicated by the list of TAs signaled to the UE.

[0036] In certain embodiments, the network can indicate the frequency of the network slice using the RedirectedCarrierlnfo in the RRCRelease message (e.g. according to 3GPP TS 38.331). However, this message transfer can only apply to RRC connected UEs. Furthermore, the signaling RedirectedCarrierlnfo in the RRCRelease message is typically used due to cell congestion situations. Thus, it will not be guaranteed that the redirection is indeed due to slice / service reasons.

[0037] The solution described below removes the dependency on the UE NAS registration procedure to signal the frequency of the network slice. The solution described below also removes the uncertainty around the existing dedicated as well as broadcast solutions by developing new signaling, new procedures and even by implementing a UE based solution.

[0038] In various embodiments, cell selection is improved by the UE initiating a frequency scan and camping on a frequency corresponding to its assumed (pre-configured) support of the most desired / preferred slice. In various embodiments, cell reselection is improved by maintaining in parallel on a second frequency.

[0039] In some embodiments, the use of the improved cell reselection can be required when the cell on carrier 'f2' not only controls cell access to establish an RRC connection but also (or only) controls cell camping, since it wants to control the RRC idle state UE load that can arise due to the network can alleviate this by e.g. broadcasting a persistence check parameter. The cell selection (reselection) on a cell on frequency 'f2' also includes this persistence check. The UE generates a random number between 0 and 1 and only if this number is smaller than the broadcasted persistence check, the UE continues to select (reselect) this cell.

[0040] Figure 1 A wireless communication system 100 for performing cell selection / reselection on a radio frequency associated with a network slice is depicted in accordance with embodiments of the present disclosure. In one embodiment, the wireless communication system 100 includes at least one remote unit 105, a radio access network (“RAN”) 120, and a mobile core network 140. The RAN 120 and mobile core network 140 form a mobile communication network. The RAN 120 can be composed of a base unit 121 with which the remote units 105 communicate using wireless communication links 123. Even though a certain number of remote units 105, base units 121, wireless communication links 123, RANs 120, and mobile core networks 140 are depicted in the figure, any number of remote units 105, base units 121, wireless communication links 123, RANs 120, and mobile core networks 140 can be included in the wireless communication system 100. Figure 1 A certain number of remote units 105, base units 121, wireless communication links 123, RANs 120, and mobile core networks 140 are depicted in the figure for purposes of illustration, and any number of remote units 105, base units 121, wireless communication links 123, RANs 120, and mobile core networks 140 can be included in the wireless communication system 100.

[0041] In one implementation, the RAN 120 is in compliance with the 5G system specified in the Third Generation Partnership Project (“3GPP”) specifications. For example, the RAN 120 can be a Next Generation Radio Access Network (“NG-RAN”) implementing New Radio (“NR”) Radio Access Technology (“RAT”) and / or Long Term Evolution (“LTE”) RAT. In another example, the RAN 120 can include non-3GPP RATs (e.g., Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 standards based RAT, Bluetooth®RAT, and / or the like). In another implementation, the RAN 120 is in compliance with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system 100 can implement some other open or proprietary communication network, such as Worldwide Interoperability for Microwave Access (“WiMAX”) or IEEE 802.16 standards, among others, and the present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. or Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 family of standards based WLAN). In another implementation, the RAN 120 is in compliance with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system 100 can implement some other open or proprietary communication network, such as Worldwide Interoperability for Microwave Access (“WiMAX”) or IEEE 802.16 standards, among others, and the present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0042] In one embodiment, the remote units 105 can include computing devices, such as desktop, laptop, personal digital assistant (“PDA”), tablet, smart phone, smart television (e.g., television connected to the Internet), smart appliance (e.g., appliance connected to the Internet), set-top box, game console, security system (including security cameras), vehicle

[0043] The remote units 105 can communicate directly with one or more of the base units 121 in the RAN 120 via uplink (“UL”) and downlink (“DL”) communication signals. The UL and DL communication signals can also be carried via wireless communication links 123. Here, the RAN 120 is an intermediate network that provides the remote units 105 with access to the mobile core network 140. As described in more detail below, the base units 121 can provide cells that operate at a first carrier frequency and / or cells that operate at a second frequency. The cells that use the first carrier frequency can form a first frequency layer, while the cells that use the second carrier frequency can form a second frequency layer.

[0044] In some embodiments, the remote units 105 communicate with the application servers 151 via a network connection with the mobile core network 140. For example, an application 107 (e.g., web browser, media client, telephone and / or Voice-over-Internet Protocol (VoIP) application) in a remote unit 105 can trigger the remote unit 105 to establish a protocol data unit (“PDU”) session (or other data connection) with the mobile core network 140 via the RAN 120. The mobile core network 140 then relays traffic between the remote unit 105 and the application server 151 in the packet data network 150 using the PDU session. The PDU session represents a logical connection between the remote unit 105 and a user plane function (“UPF”) 141.

[0045] To establish a PDU session (or PDN connection), a remote unit 105 must register with the mobile core network 140 (also referred to in the context of a Fourth Generation (“4G”) system as “attaching to the mobile core network”). Note that a remote unit 105 can establish one or more PDU sessions (or other data connections) with the mobile core network 140. Thus, a remote unit 105 can have at least one PDU session for communicating with a packet data network 150. A remote unit 105 can establish additional PDU sessions to communicate with other data networks and / or other communication peers.

[0046] In the context of a 5G system (“5GS”), the term “PDU session” refers to a data connection that provides end-to-end (“E2E”) user plane (“UP”) connectivity between a remote unit 105 and a specific data network (“DN”) through a UPF 141. A PDU session supports one or more quality of service (“QoS”) flows. In certain embodiments, there can be a one-to-one mapping between a QoS flow and a QoS profile, such that all packets belonging to a particular QoS flow have the same 5G QoS Identifier (“5QI”).

[0047] In the context of a 4G / LTE system, such as an Evolved Packet System (“EPS”), a packet data network (“PDN”) connection (also referred to as an EPS session) provides E2E UP connectivity between a remote unit and a PDN. A PDN connectivity procedure establishes an EPS bearer, i.e., a tunnel between a remote unit 105 and a packet gateway (“PGW”, not shown) in the mobile core network 140. In certain embodiments, there can be a one-to-one mapping between an EPS bearer and a QoS profile, such that all packets belonging to a particular EPS bearer have the same QoS Class Identifier (“QCI”).

[0048] A base unit 121 can be distributed across a geographic area. In certain embodiments, base units 121 can also be referred to as access terminals, access points, bases, base stations, Node-Bs (“NBs”), Evolved Node-Bs (referred to as eNodeBs, or “eNBs,” also called Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”) Node Bs), 5G / NR NodeBs (“gNBs”), home Node-Bs, relay nodes, RAN nodes, or by any other terminology used in the art. Base units 121 are generally parts of a RAN, such as RAN 120, that can include one or more controllers communicably coupled to one or more corresponding base units 121. These, and other, elements of radio access networks are not illustrated but are well known to those of ordinary skill in the art. Base units 121 connect to the mobile core network 140 via the RAN 120.

[0049] The base units 121 can serve a number of remote units 105 within a serving area, for example, a cell or a cell sector, via wireless communication links 123. The base units 121 can communicate directly with one or more of the remote units 105 via communication signals. Generally, the base units 121 transmit DL communication signals to serve the remote units 105 in the time, frequency, and / or spatial domain. Additionally, the DL communication signals can be carried via the wireless communication links 123. The wireless communication links 123 can be any suitable carrier in licensed or unlicensed radio frequency spectrum. The wireless communication links 123 facilitate communication between one or more of the remote units 105 and one or more of the base units 121. Note that during NR operation on unlicensed spectrum (referred to as “NR-U”), the base units 121 and the remote units 105 communicate via unlicensed (i.e., shared) radio frequency spectrum.

[0050] In one embodiment, the mobile core network 140 is a 5GC or an evolved packet core (“EPC”), which can be coupled to a packet data network 150, like the Internet and private data networks, among other data networks. The remote units 105 can have subscription accounts or other accounts with the mobile core network 140. In various embodiments, each mobile core network 140 belongs to a single mobile network operator (“MNO”). The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0051] The mobile core network 140 includes several network functions (“NFs”). As depicted, the mobile core network 140 includes at least one UPF 141. The mobile core network 140 also includes a number of control plane (“CP”) functions, including, but not limited to, an access and mobility management function (“AMF”) 143, a session management function (“SMF”) 145, a policy control function (“PCF”) 147, a unified data management function (“UDM”), and a user data repository (“UDR”), which serve the RAN 120. Although Figure 1 Although a specific number and type of network functions are depicted in the mobile core network 140, one of skill in the art will recognize that any number and type of network functions can be included in the mobile core network 140.

[0052] The UPF 141 is responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU session for interworking with a data network (DN) in the 5G architecture. The AMF 143 is responsible for NAS signaling termination, NAS ciphering and integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The SMF 145 is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) IP address allocation and management, DL data notification, and traffic steering configuration of UPF 141 for proper traffic routing.

[0053] The PCF 147 is responsible for unifying the policy framework, providing policy rules to CP functions, and accessing subscription information in the UDR that is used for policy decisions. The UDM is responsible for authentication and key agreement ("AKA") credential generation, user identification handling, access authorization, subscription management. The UDR is a repository of subscription information and can be used to serve a number of network functions. For example, the UDR can store subscription data, policy-related data, subscription-related data permitted to be exposed to third party applications, and the like. In some embodiments, the UDM is co-located with the UDR, depicted as the combined entity "UDM / UDR" 149.

[0054] In various embodiments, the mobile core network 140 can also include a Network Repository Function ("NRF") (which provides NF service registration and discovery, enabling NFs to identify appropriate services in each other and communicate with each other via Application Programming Interfaces ("APIs")), a Network Exposure Function ("NEF") (which is responsible for making network data and resources easily accessible by customers and network partners), an Authentication Server Function ("AUSF"), or other NFs defined for the 5GC. When present, the AUSF can function as an authentication server and / or authentication proxy, thereby allowing the AMF 143 to authenticate a remote unit 105. In certain embodiments, the mobile core network 140 can include an authentication, authorization, and accounting ("AAA") server.

[0055] In various embodiments, the mobile core network 140 supports different types of mobile data connections and different types of network slices, with each mobile data connection utilizing a particular network slice. Here, a "network slice" refers to a portion of the mobile core network 140 that is optimized for a certain traffic type or communication service. A network instance can be identified by a Single-Network Slice Selection Assistance Information ("S-NSSAI"), while a group of network slices for which the remote unit 105 is authorized to use is identified by Network Slice Selection Assistance Information ("NSSAI"). Here, "NSSAI" refers to a vector value containing one or more S-NSSAI values. In certain embodiments, the various network slices can include separate instances of network functions, such as the SMF 145 and the UPF 141. In some embodiments, different network slices can share some common network functions, such as the AMF 143. To facilitate explanation, Figure 1 Different network slices are not shown in FIG. 1, but their support is assumed. In various embodiments, a first group of network slices can be prioritized for use with a first carrier frequency, while a second group of network slices can be prioritized for use with a second carrier frequency.

[0056] Although Figure 1Components of a 5G RAN and a 5G core network are depicted, but the described embodiments for performing cell selection / reselection on a carrier frequency associated with a network slice are applicable to other types of communication networks and RATs, including IEEE 802.11 variants, Global System for Mobile Communications (“GSM,” i.e., a 2G digital cellular network), General Packet Radio Service (“GPRS”), Universal Mobile

[0057] Furthermore, in LTE variants where the mobile core network 140 is an EPC, the depicted network functions can be replaced with appropriate EPC entities, such as a Mobility Management Entity (“MME”), a Serving Gateway (“SGW”), a PGW, a Home Subscriber Server (“HSS”), and the like. For example, the AMF 143 can map to an MME, the SMF 145 can map to a control plane portion of a PGW and / or to an MME, the UPF 141 can map to an SGW and a user plane portion of a PGW, the UDM / UDR 149 can map to an HSS, etc.

[0058] In the following description, the term “RAN node” is used for a base station, but it can be replaced by any other radio access node, such as a gNB, an eNB, a base station (“BS”), an access point (“AP”), etc. Moreover, the operations are primarily described in the context of 5G NR. However, the proposed solutions / methods can equally be applicable to other mobile communication systems that support cell selection / reselection on a carrier frequency associated with a network slice.

[0059] Figure 2 A NR protocol stack 200 is depicted in accordance with an embodiment of the present disclosure. While the protocol stack 200 is described in the context of a 5G NR network, the described embodiments are equally applicable to other mobile communication systems that support cell selection / reselection on a carrier frequency associated with a network slice. Figure 2 A UE 205, a RAN node 210, and an AMF 215 in a 5G core network (“5GC”) are shown, but these represent a set of remote units 105 that interact with base units 121 and a mobile core network 140. As depicted, the protocol stack 200 includes a user plane protocol stack 201 and a control plane protocol stack 203. The user plane protocol stack 201 includes a physical (“PHY”) layer 220, a medium access control (“MAC”) sublayer 225, a radio link control (“RLC”) sublayer 230, a packet data convergence protocol (“PDCP”) sublayer 235, and a service data adaptation protocol (“SDAP”) layer 240. The control plane protocol stack 203 includes the physical layer 220, the MAC sublayer 225, the RLC sublayer 230, and the PDCP sublayer 235. The control plane protocol stack 203 also includes a radio resource control (“RRC”) layer 245 and a non-access stratum (“NAS”) layer 250.

[0060] The AS layers of the user plane protocol stack 201 (also referred to as the “AS protocol stack”) are comprised of at least the SDAP, PDCP, RLC, and MAC sub-layers, and the physical layer. The AS layers of the control plane protocol stack 203 are comprised of at least the RRC, PDCP, RLC, and MAC sub-layers, and the physical layer. Layer 2 (“L2”) is split into the SDAP, PDCP, RLC, and MAC sub-layers. Layer 3 (“L3”) includes the RRC sub-layer 245 of the control plane and the NAS layer 250, and includes, e.g., the Internet Protocol (“IP”) layer and / or PDU layer (not depicted) of the user plane. L1 and L2 are referred to as “lower layers,” while L3 and above (e.g., transport layer, application layer) are referred to as “higher layers” or “upper layers.”

[0061] The physical layer 220 provides transport channels to the MAC sub-layer 225. The physical layer 220 can perform clear channel assessment and / or listen-before-talk (“CCA / LBT”) procedures using an energy detection threshold, as described herein. In certain embodiments, the physical layer 220 can send a notification of a UL listen-before-talk (“LBT”) failure to a MAC entity at the MAC sub-layer 225. The MAC sub-layer 225 provides logical channels to the RLC sub-layer 230. The RLC sub-layer 230 provides RLC channels to the PDCP sub-layer 235. The PDCP sub-layer 235 provides radio bearers to the SDAP sub-layer 240 and / or the RRC layer 245. The SDAP sub-layer 240 provides QoS flows to the core network (e.g., 5GC). The RRC layer 245 provides addition, modification, and release of carrier aggregation and / or dual connectivity. The RRC layer 245 also manages the establishment, configuration, maintenance, and release of signaling radio bearers (“SRBs”) and data radio bearers (“DRBs”).

[0062] The NAS layer 250 is between the UE 205 and the 5GC 215. NAS messages are passed transparently through the RAN. The NAS layer 250 is used to manage the establishment of communication sessions and to maintain continuous communication with the UE 205 as the UE 205 moves between different cells of the RAN. In contrast, the AS layers carry information between the UE 205 and the RAN (i.e., the RAN nodes 210) and via the wireless portion of the network.

[0063] Figure 3An example network deployment 300 depicting a RAN portion of a mobile communication network according to embodiments of the disclosure. The RAN 301 can support multiple frequency layers, as described in more detail below. In the depicted embodiment, a UE 205 is in the coverage area of a first cell 305 operating on a first frequency. Here, the first cell 305 is part of a first frequency layer 310 that supports a first set of network slices 311. For example, a slice supporting a first service 'i' (depicted as "Slice-i") and a slice supporting a second service 'ii' (depicted as "Slice-ii") can be part of the first set of network slices 311. The first cell 305 can represent any cell on the first frequency layer 310.

[0064] As shown, the UE 205 is also within the coverage area of a second cell 315 operating on a second frequency different from the first frequency. Here, the second cell 315 is part of a second frequency layer 320 that supports a second set of network slices 321 different from the first set 311. For example, a slice supporting a first service 'x' (depicted as "Slice-x") and a slice supporting a second service 'y' (depicted as "Slice-y") can be part of the second set of network slices 321. Here, the second cell 315 can represent any cell on the second frequency layer 320.

[0065] In one embodiment, the first frequency layer 310 does not support any of the second set of network slices 321. In other embodiments, a cell of the first frequency layer 310 can support one or more of the slices in the second set of network slices 321; however, where possible, the mobile communication network can prefer to use the slices in the second set of network slices 321 in the second frequency, e.g., if the priority of the second set of network slices is higher when served on the second frequency layer. The priority of a set of network slices can be determined in the UE based on implementation including user input, or the priority can be signaled by the network using RRC or NAS signaling. In addition to this, among the slices subscribed by the UE or allowed by the network for a given UE, some slices can have higher priority than others and thus the UE can perform cell selection (reselection) to be able to cater to the most preferred / prioritized slice. If the higher (or most) prioritized / preferred slice is better served on a different frequency layer, the UE maintains parallel mobility on those two layers.

[0066] In the depicted embodiment, it is assumed that the network operator prefers the UE 205 to camp on a carrier of the first frequency layer 310, e.g., due to the first frequency layer providing greater geographical coverage. As used herein, "camping" refers to the behavior of the UE 205 in the RRC idle state, where the UE 205 has selected a cell and is ready to initiate an RRC connection, receive paging, and receive broadcast services. Note that when in the RRC idle state, the UE 205 is on but does not have any RRC connection established with the mobile communication network.

[0067] In some embodiments, when the UE 205 transitions from the RRC connected state to the RRC idle state, the UE 205 selects a cell to camp on. This cell can be a cell on the frequency indicated in the RRC connection release message. When camping on the cell, the UE 205 can monitor and receive system information broadcast in the cell. Further, the UE 205 can perform cell reselection when camping on the overlaying cell.

[0068] However, the UE 205 can have a preferred slice (also referred to as a 'desired' slice) as part of the second set of network slices 321. As used herein, a 'preferred slice' or 'desired slice' refers to a slice that is part of a list of allowed slices, a list of rejected slices, a list of configured slices, etc. In various embodiments, the mobile communication network is aware of the 'desired' list of slices, e.g., based on a registration procedure performed by the UE 205. In various embodiments, the UE 205 assumes that the first entry in the dedicated signaling cellReselectionPriorities list corresponds to its most desired slice. For example, the most desired slice can be the highest priority slice.

[0069] To minimize the delay when connecting to the second cell 315, the UE 205 performs parallel maintenance of the second frequency layer 320. Thus, while the UE 205 considers that it will camp on the first frequency layer (e.g., frequency 'fl'), the parallel maintenance allows the UE 205 to very quickly establish an RRC connection with the second cell 315 whenever the UE 205 needs a connection from the upper layers for service 'x'. To save power, the UE 205 should not be required to continuously monitor the first frequency layer (i.e., frequency 'f2'). The solution described below provides an optimization between the power consumption at the UE 205 (which is camping on the cell 305) and the time for establishing an RRC connection with the second cell 315.

[0070] The first frequency layer 310 is a set of cells (or cell sectors) operating on the same carrier frequency (i.e., the first frequency 'fl'). In the depicted embodiment, the first frequency layer includes the following cells: cell-1, cell-2, cell-3, and cell-4. Here, the first set of network slices 311 is prioritized for use with the frequency 'fl'. Thus, the UE 205 can be configured to camp on the first frequency layer 310 when within a particular geographic zone. In some embodiments, the geographic coverage areas of the cells in the first frequency layer 310 can be contiguous.

[0071] The second frequency layer 320 is a second set of cells (or cell sectors) operating on the same carrier frequency (i.e., the second frequency 'f2'). In the depicted embodiment, the second frequency layer includes the following cells: cell-a, cell-b, cell-c, and cell-d. Here, the second set of network slices 321 is prioritized for use with the frequency 'f2'. In the depicted embodiment, the geographic coverage areas of the cells of the second frequency layer 320 are not contiguous. However, in other embodiments, one or more cells of the second frequency layer 320 can have contiguous coverage areas.

[0072] According to the first solution, cell selection is improved by the UE (i.e., one embodiment of the remote unit 105) initiating a frequency scan and / or cell search on a frequency corresponding to the frequency that it assumes (preconfigures) supports the most desired slice. In effect, this would mean that for ultra-reliable low latency communication ("URLLC") services, the UE 205 would start its scan under / near the frequency 'f2' (e.g., under / near 4.9 GHz).

[0073] In some embodiments of the first solution, the UE 205 maintains a table mapping network slices (i.e., in priority order) to corresponding frequencies. Here, a higher layer entity (e.g., a NAS entity) can inform the AS layer of the frequency / slice combinations that should be searched (e.g., for Figure 3 the desired network slice of the example deployment of frequency 'f2'). For example, the NAS layer entity can indicate that the AS layer should search for the frequency / slice combination corresponding to the preferred network slice.

[0074] As used herein, cell selection refers to the selection of a suitable cell using information collected during a cell search and / or using previously stored information. Here, the UE 205 uses cell selection criteria (e.g., signal strength, signal quality, service type, etc.) to select a cell. In certain embodiments, the UE 205 performs cell selection as described in 3GPP TS 36.304.

[0075] As used herein, cell search refers to the combined procedure of detection / scanning, measurement, and evaluation. Detection (also referred to as scanning) refers to tuning to a particular carrier frequency (e.g., 'fi' or 'f2') and identifying candidates for measurement. In the measurement phase, the UE 205 measures the signal strength of the candidate cells, such as the reference signal received power ("RSRP") and / or the reference signal received quality ("RSRQ"). In the evaluation phase, the UE 205 checks cell selection criteria using the measurement results.

[0076] According to a second solution, the UE 205 improves cell reselection by maintaining the second frequency layer 320 in parallel while the UE 205 camps on the first frequency layer 310 (i.e., when in RRC idle state). Here, the UE 205 performs detection, measurement and evaluation of the second frequency layer (i.e., carrier frequency 'f2') while camping on the cell of the first frequency layer 310 (i.e., carrier frequency 'f1').

[0077] In some embodiments, the UE 205 keeps performing a "virtual" reselection on the second frequency layer 320. Here, the term "virtual" is used because the UE has not yet registered on a cell of the second frequency layer 320 (recall that the UE 205 is in RRC idle state). This means that the UE 205 behaves internally as if it also camps on the second cell 315 and is trying to reselect a cell on the second frequency layer 320. However, from the network perspective, the UE 205 is camping on the first frequency layer 310 (i.e., the UE 205 is paged on a cell of the first frequency layer 310 and only requests system information ("SI") from the cell of the first frequency layer 310 on demand). When application data for service 'x' is available, the UE can establish an RRC connection from the currently selected (i.e., virtually camped) cell on the second frequency layer 320. Note that establishing an RRC connection includes transitioning from RRC idle state to RRC connected state.

[0078] In the above case, assume that the first set of network slices 311 is associated with a first group of applications and the second set of network slices 321 is associated with a second group of applications. Thus, when application data is generated by an application of the first group of applications, then the UE 205 needs a connection to the first set of network slices 311 and thus performs cell selection for the first frequency layer 310 and establishes an RRC connection with the selected cell (e.g., first cell 305). In contrast, when application data is generated by an application of the second group of applications, then the UE 205 needs a connection to the second set of network slices 321 and thus performs cell selection for the second frequency layer 320 and establishes an RRC connection with the selected cell (e.g., second cell 315).

[0079] To save power during parallel maintenance, one or more of the following options can be employed. According to a first power saving option, the UE 205 can perform only a subset of the cell search tasks (i.e., not all of the detection, measurement and evaluation of f2) on the second frequency layer 320. For example, the UE 205 can perform only detection and (optionally) measurement of a cell on the second frequency layer 320. In one embodiment, performing only a subset of the cell search tasks can occur every time a cell search is performed for the second frequency layer 320. In another embodiment, performing only a subset of the cell search tasks can occur every time a cell search is performed for the second frequency layer 320.

[0080] As another example, the UE 205 can perform a cell search on the second frequency layer 320 with reduced performance. In one embodiment, performing a cell search with reduced performance includes performing a cell search on the second frequency layer 320 with longer intervals (i.e., longer periodicity) than used for the first frequency layer 310. In another embodiment, performing a cell search with reduced performance includes increasing a detection threshold to reduce the number of candidate cells to be measured.

[0081] According to a second power saving option, a less mobile or stationary UE 205 camps on the second frequency layer 320 rather than the first frequency layer 310. Thus, if the mobility level of the UE 205 is below a predefined mobility threshold, the UE 205 camps on a cell of the second frequency layer 320.

[0082] According to a third option, the UE 205 determines the interval to perform a cell search on the second frequency layer 320, e.g., based on battery power or based on power consumption level. For example, a PPI (power performance trade-off) necessitates a UE 205 decision whether to do parallel reselection (i.e., parallel maintenance of the second frequency in RRC idle) always or only limited, e.g., depending on battery constraints.

[0083] As used herein, cell reselection refers to a UE 205 that has selected a cell and decides to re-perform cell selection, e.g., in response to a trigger condition. In one embodiment, the trigger condition is expiration of a timer. In another embodiment, the trigger condition is that RSRP and / or RSRQ measurements of the currently selected cell deteriorate (e.g., drop below a threshold). During cell reselection, the UE 205 performs the above-described steps of cell selection. In certain embodiments, the UE 205 performs a cell search again during the cell reselection procedure. In some embodiments, cell reselection can evaluate additional criteria that were not evaluated during initial cell selection. In some embodiments, the UE 205 considers cell priorities when performing cell reselection.

[0084] According to a third solution, the mobile communication network (e.g., RAN) can control the RRC idle state UE load of a cell using a persistence check parameter. When a cell on the second frequency layer 320 not only controls cell access to establish an RRC connection but also (or only) does cell camping to thereby affect the RRC idle state UE load, the use of an improved cell reselection with parallel maintenance can be needed.

[0085] RRC idle state UE load can arise due to 1) higher number of UEs in RRC idle will mean higher number of UEs requesting SI on demand; 2) higher number of UEs in RRC idle will mean higher number of attempts to establish RRC connection for MO (mobile originated) calls; and / or 3) higher number of UEs in RRC idle will mean higher paging load, higher number of attempts to establish RRC connection for MT (mobile terminated) calls.

[0086] The persistence check parameter is a value selected based on the RRC idle state load. In one embodiment, the persistence check parameter is a decimal number between 0 and 1 (e.g., 0.3). To mitigate the RRC idle state UE load, a cell in the RAN can, for example, broadcast the persistence check parameter.

[0087] At the UE side, the cell selection / reselection procedure on this cell implementing this persistence check is modified as follows: the UE 205 generates a random value (e.g., a decimal number between 0 and 1) within the allowed range of the persistence check parameter and compares the generated value to the persistence check parameter. The UE 205 selectively stops the cell selection / reselection procedure based on the comparison. In one embodiment, the UE 205 continues to select / reselect this cell only if the generated random value is less than the broadcasted persistence check parameter. In another embodiment, the UE 205 continues to select / reselect this cell only if the generated random value is greater than the broadcasted persistence check parameter.

[0088] According to a fourth solution, the UE 205 performs cell search for the second frequency layer 320 at different intervals based on the relative priority of the second frequency layer 320. For example, the UE 205 can determine that the second frequency layer 320 has a higher frequency (relative to other frequency layers of the RAN) based on a dedicated priority or based on a common priority of the carrier frequency of the second frequency layer (i.e., 'f2'). With respect to the dedicated priority, the RRC connection release message provides the UE 205 with radio resources during the release of the UE radio resources (i.e., in the IdleModeMobilityControlInfo information element ("IE")).

[0089] With respect to the common priority, the priority of the serving frequency can be specified and broadcasted by the RAN in system information (e.g., in system information block ("SIB") 3). The priority of the non-serving frequencies can be specified and broadcasted in SIB 5, while the priority of the frequencies using different RATs can be broadcasted in another SIB (e.g., SIB 6, SIB 7, and / or SIB 8). As applied to the example deployment of Figure 3 The UE 205 camped on the first cell 305 can identify the priority of the first frequency layer 310 from SIB 3 and the priority of the second frequency layer 320 from SIB 5.

[0090] In various embodiments, the second frequency layer 320 can have a greater relative priority. Thus, the UE 205 can perform a cell search procedure (or portions thereof) for the higher priority frequency at a higher interval. In one embodiment, the UE 205 performs a cell search for the higher priority frequency layer at least every T higher_priority_search = (60 x N layers ) seconds.

[0091] Further, the UE 205 can know that the second frequency layer 320 (i.e., 'f2') supports its preferred / expected slice (e.g., based on stored information, or the network can inform the UE of this information). Thus, the UE 205 knows that the second frequency layer 320 supports its preferred slice, and searches that frequency layer (F2) more frequently than searches for other frequency layers. In one embodiment, cell searches in the frequency layers F2, F3, and F4 occur according to a pattern that increases the frequency with which the preferred frequency layer (i.e., F2) is searched. For example, the search order can be <F2, F3, F2, F4, F2, F3>, etc., rather than <F2, F3, F4, F2, F3, F4>, etc. In another variation of this solution, one or more frequencies associated with non-preferred slices can be de-prioritized or omitted from inter-frequency reselection.

[0092] According to a fifth solution, a dedicated or cell-common priority can configure the second frequency layer 320 to have a low priority. In some embodiments, the network informs the UE that the second frequency layer 320 supports the preferred / expected slice. In other embodiments, the UE 205 knows that the second frequency layer 320 supports the preferred / expected slice based on stored information. Here, the UE 205 performs inter-frequency reselection to find a cell of the second frequency layer 320 even when the camped-on cell (i.e., the first cell 305) remains above a quality threshold.

[0093] Figure 4 A user equipment device 400 that can be used to perform cell selection / reselection on carrier frequencies associated with network slices, in accordance with embodiments of the present disclosure, is depicted. In various embodiments, the user equipment device 400 is used to implement one or more of the solutions described above. The user equipment device 400 can be one embodiment of the remote units 105 and / or UE 205 described above. Furthermore, the user equipment device 400 can include a processor 405, a memory 410, an input device 415, an output device 420, and a transceiver 425.

[0094] In some embodiments, the input device 415 and the output device 420 are combined into a single device, such as a touch screen. In certain embodiments, the user equipment apparatus 400 can not include any input device 415 and / or output device 420. In various embodiments, the user equipment apparatus 400 can include one or more of the processor 405, the memory 410, and the transceiver 425, and can not include the input device 415 and / or the output device 420.

[0095] As depicted, the transceiver 425 includes at least one transmitter 430 and at least one receiver 435. In some embodiments, the transceiver 425 communicates with one or more cells (or wireless coverage areas) supported by one or more base units 121. In various embodiments, the transceiver 425 can operate on unlicensed spectrum. Further, the transceiver 425 can include multiple UE panels supporting one or more beams. Additionally, the transceiver 425 can support at least one network interface 440 and / or application interface 445. The application interface 445 can support one or more APIs. The network interface 440 can support 3GPP reference points, such as Uu, Nl, PC5, etc. Other network interfaces 440 can be supported as understood by those skilled in the art.

[0096] In one embodiment, the processor 405 can include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 405 can be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor 405 executes instructions stored in the memory 410 to perform methods and routines described herein. The processor 405 is communicatively coupled to the memory 410, the input device 415, the output device 420, and the transceiver 425.

[0097] In various embodiments, the processor 405 controls the user equipment apparatus 400 to implement the UE behaviors described above. In certain embodiments, the processor 405 can include an application processor (also known as a “main processor”) that manages application domains and operating system (“OS”) functions, and a baseband processor (also known as a “baseband wireless processor”) that manages radio functions.

[0098] In various embodiments, the processor 405 controls the user equipment device 400 to implement the UE behaviors described above. For example, the processor 405 can control the transceiver 425 to camp on a first frequency layer of a RAN while in an RRC idle state, where the first frequency layer supports a first set of network slices. Additionally, the processor 405 iteratively performs cell search on a second frequency layer while camped on the first frequency layer, where the second frequency layer supports a second set of network slices. Here, the device 400 is configured to use the first set of network slices and the second set of network slices, where the first set of network slices is prioritized for use with a first frequency (i.e., corresponding to the first frequency layer), and the second set of network slices is prioritized for use with a second frequency (i.e., corresponding to the second frequency layer).

[0099] The processor 405 maintains the second frequency layer in parallel while in the RRC idle state by performing cell reselection on the second frequency. In some embodiments, maintaining the second frequency layer in parallel includes maintaining (e.g., continuously monitoring and evaluating cell reselection) both the first frequency layer and the second frequency layer. In certain embodiments, maintaining the second frequency layer in parallel includes performing a “virtual” reselection for the second frequency layer, as described above.

[0100] In some embodiments, the first set of network slices is associated with a first group of applications, and the second set of network slices is associated with a second group of applications. In certain embodiments, the first frequency layer comprises a set of one or more first cells (or cell sectors) in the RAN operating on the first frequency. In certain embodiments, the second frequency layer comprises a set of one or more second cells (or cell sectors) in the RAN operating on the second frequency.

[0101] In some embodiments, the processor 405 iteratively performs cell search on the second frequency layer while camped on the first frequency layer by performing cell search on the second frequency layer with reduced performance compared to performance of cells on the first frequency layer. Note that performing cell search for a particular frequency layer can include performing steps of detection, measurement, and evaluation of cells on the particular frequency layer. In one embodiment, the processor 405 iteratively performs cell search on the second frequency layer by performing cell search on the second frequency layer with longer intervals (i.e., less frequently) than for the first frequency layer. In another embodiment, the processor 405 iteratively performs cell search on the second frequency layer with reduced performance by skipping one or more evaluation steps of iterations for cell search on the second frequency layer.

[0102] In some embodiments, the processor 405 determines an interval for performing a cell search on a second frequency layer while camped on a first frequency layer, the interval determined based on a battery power level of the device 400 or based on a power consumption level of the device 400. In some embodiments, the processor 405 controls the transceiver 425 to camp on the second frequency layer, rather than the first frequency layer, in response to a mobility level of the device 400 being below a predefined mobility threshold.

[0103] In some embodiments, the processor 405 determines that the second frequency layer has a higher priority than other frequency layers of the RAN and in response performs an optimized cell search on the second frequency layer using an interval shorter than a search interval associated with a lower priority frequency layer of the RAN. In certain embodiments, the processor 405 further excludes one or more frequency layers not associated with the preferred slice from consideration for inter- frequency reselection.

[0104] In some embodiments, the processor 405 determines that the second frequency has a lower priority, for example, based on a dedicated priority of the second frequency or based on a common priority of the second frequency. In such embodiments, the processor 405 can perform inter- frequency reselection for the second frequency even when a quality level of the first frequency satisfies a quality threshold.

[0105] In some embodiments, the processor 405 maintains a prioritized table mapping network slices to corresponding frequencies and initiates a frequency scan for a second frequency while camped on a first frequency layer. In such embodiments, a NAS layer entity in the device 400 can inform an AS layer entity in the device 400 to search for a specific combination of a frequency and a network slice, the combination corresponding to a preferred network slice.

[0106] In some embodiments, the processor 405 detects a request to establish a data connection with a network slice of the second set of network slices and establishes an RRC connection with a cell on the second frequency layer in response to detecting the request. In such embodiments, the request can be generated by an application running on the device 400 and / or by an operating system of the device 400.

[0107] In various embodiments, the transceiver 425 receives a broadcast message including a persistence check value of a cell. Thereafter, during a cell reselection procedure, the processor 405 can generate a random value and compare the generated random value to the received persistence check value. Based on a result of the comparison, the processor 405 selectively stops the cell reselection procedure.

[0108] In certain embodiments, the processor 405 selectively stops the cell reselection based on the result of the comparison by continuing the cell reselection in response to the generated random value being less than the received persistence check value. Otherwise, if the generated random value is not less than the received persistence check value, the processor 405 stops the cell reselection procedure (i.e., terminates the procedure without selecting / reselecting a cell). In alternative embodiments, the processor 405 can continue / complete the cell reselection procedure when the generated random value is greater than the received persistence check value and terminate the cell reselection procedure when the generated random value is not greater than the received persistence check value.

[0109] In some embodiments, the persistence check value is selected based on an RRC idle state UE load of the first cell. In some embodiments, the persistence check value is configured by the mobile communication network using RRC signaling.

[0110] In one embodiment, the memory 410 is a computer readable storage medium. In some embodiments, the memory 410 includes volatile computer storage media. For example, the memory 410 can include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, the memory 410 includes non-volatile computer storage media. For example, the memory 410 can include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 410 includes both volatile and non-volatile computer storage media.

[0111] In some embodiments, the memory 410 stores data related to cell selection / reselection on a carrier frequency associated with a network slice. For example, the memory 410 can store various parameters, panel / beam configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory 410 also stores program code and related data, such as an operating system or other controller algorithms operating on the device 400.

[0112] In one embodiment, the input device 415 can include any known computer input device, including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device 415 can be integrated with the output device 420, as in a touchscreen or similar touch-sensitive display. In some embodiments, the input device 415 includes a touchscreen such that text can be input using a virtual keyboard displayed on the touchscreen and / or by handwriting on the touchscreen. In some embodiments, the input device 415 includes two or more different devices, such as a keyboard and a touch panel.

[0113] In one embodiment, output device 420 can be designed to output visual, audible, and / or tactile signals. In some embodiments, output device 420 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 420 can include, but is not limited to, a liquid crystal display (“LCD”) display, a light emitting diode (“LED”) display, an organic LED (“OLED”) display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, output device 420 can include a wearable display separate from, but communicatively coupled to, the remainder of user equipment apparatus 400, such as a smartwatch, smartglasses, a head-mounted display, or the like. Further, output device 420 can be a component of a smart-phone, a personal data assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0114] In certain embodiments, output device 420 includes one or more speakers for producing sound. For example, output device 420 can produce an audible alert or notification (such as a beep or chime). In some embodiments, output device 420 includes one or more haptic devices for producing vibrations, motion, or other tactile feedback. In some embodiments, output device 420 can be integrated in whole or in part with input device 415. For example, input device 415 and output device 420 can form a touchscreen or similar touch-sensitive display. In other embodiments, output device 420 can be positioned adjacent to input device 415.

[0115] Transceiver 425 communicates with one or more network functions of a mobile communication network via one or more access networks. Transceiver 425 operates under the control of processor 405 to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, processor 405 can selectively activate transceiver 425 (or portions thereof) at particular times in order to send and receive messages.

[0116] The transceiver 425 includes at least one transmitter 430 and at least one receiver 435. The one or more transmitters 430 can be used to provide UL communication signals to a base unit 121, for example, UL transmissions described herein. Similarly, the one or more receivers 435 can be used to receive DL communication signals from the base unit 121, as described herein. Although only one transmitter 430 and one receiver 435 are illustrated, the user equipment device 400 can have any suitable number of transmitters 430 and receivers 435. Further, the transmitter 430 and receiver 435 can be any suitable type of transmitters and receivers. In one embodiment, the transceiver 425 includes a first transmitter / receiver pair for communicating with a mobile communication network via licensed radio spectrum and a second transmitter / receiver pair for communicating with a mobile optical communication network via unlicensed radio spectrum.

[0117] In certain embodiments, the first transmitter / receiver pair for communicating with a mobile communication network via licensed radio spectrum and the second transmitter / receiver pair for communicating with a mobile communication network via unlicensed radio spectrum can be combined into a single transceiver unit, for example, a single chip that performs functions to be used with both licensed and unlicensed radio spectrum. In some embodiments, the first transmitter / receiver pair and the second transmitter / receiver pair can share one or more hardware components. For example, certain transceivers 425, transmitters 430, and receivers 435 can be implemented as physically separate components that access shared hardware and / or software resources, for example, the network interface 440.

[0118] In various embodiments, the one or more transmitters 430 and / or the one or more receivers 435 can be implemented and / or integrated into a single hardware component, such as a multi-transceiver chip, a single chip system, an application specific integrated circuit ("ASIC"), or other type of hardware component. In certain embodiments, the one or more transmitters 430 and / or the one or more receivers 435 can be implemented and / or integrated into a multi-chip module. In some embodiments, other components, such as the network interface 440 or other hardware components / circuits, can be integrated with any number of transmitters 430 and / or receivers 435 into a single chip. In such embodiments, the transmitters 430 and receivers 435 can be logically configured as a transceiver 425 that uses one or more common control signals or as modular transmitters 430 and receivers 435 that are implemented in the same hardware chip or multi-chip module.

[0119] Figure 5A network device 500 that can be used to perform cell selection / reselection on a carrier frequency associated with a network slice is depicted in accordance with embodiments of the present disclosure. In one embodiment, the network device 500 can be one implementation of a RAN node, such as the base unit 121 and / or RAN node 210 as described above. Furthermore, the network device 500 can include a processor 505, a memory 510, an input device 515, an output device 520, and a transceiver 525.

[0120] In some embodiments, the input device 515 and the output device 520 are combined into a single device, such as a touch screen. In certain embodiments, the network device 500 can not include any input device 515 and / or output device 520. In various embodiments, the network device 500 can include one or more of the processor 505, the memory 510, and the transceiver 525, and can not include the input device 515 and / or the output device 520.

[0121] As depicted, the transceiver 525 includes at least one transmitter 530 and at least one receiver 535. Here, the transceiver 525 communicates with one or more remote units 105. Additionally, the transceiver 525 can support at least one network interface 540 and / or application interface 545. The application interface 545 can support one or more APIs. The network interface 540 can support 3GPP reference points, such as Uu, Nl, N2, and N3. Other network interfaces 540 can be supported, as understood by one of ordinary skill in the art.

[0122] In one embodiment, the processor 505 can include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 505 can be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processor, a FPGA, or similar programmable controller. In some embodiments, the processor 505 executes instructions stored in the memory 510 to perform methods and routines described herein. The processor 505 is communicatively coupled to the memory 510, the input device 515, the output device 520, and the transceiver 525.

[0123] In various embodiments, the network device 500 is a RAN node (e.g., gNB) that communicates with one or more UEs, as described herein. In such embodiments, the processor 505 controls the network device 500 to perform the RAN behaviors described above. When operating as a RAN node, the processor 505 can include an application processor (also known as “main processor”) that manages application domains and operating system (“OS”) functions, and a baseband processor (also known as “baseband radio processor”) that manages radio functions.

[0124] In various embodiments, the network device 500 provides one or more cells on one or more frequency layers. In some embodiments, the processor 505 can configure a UE to use a first set of network slices and a second set of network slices, where the first set of network slices is prioritized for use with a first frequency and the second set of network slices is prioritized for use with a second frequency. Note that the processor 505 can control the transceiver 525 to provide a first cell operating on the first frequency and / or a second cell operating on the second frequency. As described above, a first frequency layer including one or more first cells operating on the first frequency can support the first set of network slices, while a second frequency layer (i.e., including one or more second cells operating on the second frequency) can support the second set of network slices.

[0125] In some embodiments, the processor 505 can control the transceiver 525 to broadcast a message in a cell, the message including a persistence check value for the cell. Here, the processor 505 can select the persistence check value based on an RRC idle state UE load of the cell at which the message is broadcast.

[0126] In one embodiment, the memory 510 is a computer readable storage medium. In some embodiments, the memory 510 includes volatile computer storage media. For example, the memory 510 can include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, the memory 510 includes non-volatile computer storage media. For example, the memory 510 can include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 510 includes both volatile and non-volatile computer storage media.

[0127] In some embodiments, the memory 510 stores data related to cell selection / deselection on carrier frequencies associated with network slices. For example, the memory 510 can store parameters, configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory 510 also stores program code and related data, such as an operating system or other controller algorithms operating on the device 500.

[0128] In one embodiment, the input device 515 can include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device 515 can be integrated with the output device 520, e.g., as a touchscreen or similar touch-sensitive display. In some embodiments, the input device 515 includes a touchscreen such that text can be input using a virtual keyboard displayed on the touchscreen and / or by handwriting on the touchscreen. In some embodiments, the input device 515 includes two or more different devices, such as a keyboard and a touch panel.

[0129] In one embodiment, output device 520 can be designed to output visual, audible, and / or tactile signals. In some embodiments, output device 520 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 520 can include, but is not limited to, an LCD display, LED display, OLED display, projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, output device 520 can include a wearable display separate from, but communicatively coupled to, the remainder of network equipment 500, such as a smartwatch, smartglasses, a head-mounted display, or the like. Further, output device 520 can be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0130] In certain embodiments, output device 520 includes one or more speakers for producing sound. For example, output device 520 can produce an audible alert or notification (e.g., a beep or chime). In some embodiments, output device 520 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, output device 520 can be integrated in whole or in part with input device 515. For example, input device 515 and output device 520 can form a touchscreen or similar touch-sensitive display. In other embodiments, output device 520 can be positioned near input device 515.

[0131] Transceiver 525 includes at least one transmitter 530 and at least one receiver 535. Similarly, one or more transmitters 530 can be used to communicate with UEs, as described herein. One or more receivers 535 can be used to communicate with network functions in a public land mobile network (“PLMN”) and / or a RAN, as described herein. Although only one transmitter 530 and one receiver 535 are illustrated, the network equipment 500 can have any suitable number of transmitters 530 and receivers 535. Further, the transmitter(s) 530 and the receiver(s) 535 can be any suitable type of transmitters and receivers.

[0132] Figure 6 One embodiment of a method 600 for parallel maintenance of a second frequency layer is depicted in accordance with embodiments of the present disclosure. In various embodiments, the method 600 is performed by a user equipment device in a mobile communication network, such as the remote units 105, the UE 205, and / or the user equipment apparatus 400 described above. In some embodiments, the method 600 is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0133] The method 600 begins and configures 605 a UE to use a first set of network slices and a second set of network slices. The method 600 includes camping 610 on a first frequency layer of a RAN while in an RRC idle state, the first frequency layer supporting the first set of network slices, wherein the first set of network slices is prioritized for use with the first frequency. The method 600 includes iteratively performing 615 a cell search on a second frequency layer while the UE is camped on the first frequency layer, the second frequency layer supporting the second set of network slices, wherein the second set of network slices is prioritized for use with the second frequency. The method 600 includes concurrently maintaining 620 the second frequency layer while in the RRC idle state by performing a cell reselection on the second frequency. The method 600 ends.

[0134] Figure 7 One embodiment of a method 700 for cell reselection using a persistent check value is depicted in accordance with an embodiment of the present disclosure. In various embodiments, the method 700 is performed by a user equipment device in a mobile communication network, such as the remote unit 105, UE 205, and / or user equipment apparatus 400 described above. In some embodiments, the method 700 is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0135] The method 700 begins and receives 705 a broadcast message including a persistent check value for a first cell. The method 700 includes generating 710 a random value during a cell reselection procedure. The method 700 includes comparing 715 the generated random value to the persistent check value. The method 700 includes selectively stopping 720 the cell reselection based on a result of the comparison. The method 700 ends.

[0136] A first device for performing cell selection / reselection on a radio carrier frequency associated with a network slice is disclosed herein in accordance with an embodiment of the present disclosure. The first device can be implemented by a user equipment device in a mobile communication network, such as the remote unit 105, UE 205, and / or user equipment apparatus 400 described above. The first device includes a processor and a transceiver that camps on a first frequency layer of a RAN while in an RRC idle state, the first frequency layer supporting a first set of network slices. The processor iteratively performs a cell search on a second frequency layer while the device is camped on the first frequency layer, the second frequency layer supporting a second set of network slices. Here, the first device is configured to use the first set of network slices and the second set of network slices, wherein the first set of network slices is prioritized for use with the first frequency (i.e., corresponding to the first frequency layer) and the second set of network slices is prioritized for use with the second frequency (i.e., corresponding to the second frequency layer). The processor concurrently maintains the second frequency layer while in the RRC idle state by performing a cell reselection on the second frequency.

[0137] In some embodiments, the first set of network slices is associated with a first group of applications and the second set of network slices is associated with a second group of applications. In certain embodiments, the first frequency layer comprises a set of one or more first cells (or cell sectors) in the RAN operating on a first frequency. In certain embodiments, the second frequency layer comprises a set of one or more second cells (or cell sectors) in the RAN operating on a second frequency.

[0138] In some embodiments, iteratively performing cell search on the second frequency layer while camped on the first frequency layer includes performing detection, measurement, and evaluation of cells on the second frequency layer with reduced performance compared to detection, measurement, and evaluation of cells on the first frequency layer. In one embodiment, performing the above operations with reduced performance means performing with longer intervals. In another embodiment, performing with reduced performance means skipping one or more iteration of the evaluation step.

[0139] In some embodiments, the processor determines an interval for performing cell search on the second frequency layer while the device is camped on the first frequency layer, the interval determined based on a battery power level of the device or based on a power consumption level of the device. In some embodiments, the processor controls the transceiver to camp on the second frequency layer, instead of the first frequency layer, in response to a mobility level of the device being below a predefined mobility threshold.

[0140] In some embodiments, the processor determines that the second frequency layer has a higher priority than other frequency layers of the RAN and performs an optimized cell search on the second frequency layer by using an interval shorter than a search interval associated with a lower priority frequency layer of the RAN. In certain embodiments, the processor further excludes one or more frequency layers not associated with a preferred slice from consideration for inter-frequency reselection.

[0141] In some embodiments, the processor determines that the second frequency has a lower priority, for example, based on a dedicated priority of the second frequency or based on a common priority of the second frequency. In such embodiments, the processor performs inter-frequency reselection for the second frequency even when a quality level of the first frequency meets a quality threshold.

[0142] In some embodiments, the processor maintains a prioritized table mapping network slices to corresponding frequencies and initiates a frequency scan for the second frequency while camped on the first frequency layer. In such embodiments, a NAS layer entity in the device can inform an AS layer entity in the device to search for a specific combination of frequency and network slice, the combination corresponding to a preferred network slice.

[0143] In some embodiments, the processor detects a request to establish a data connection with a network slice of the second set of network slices and establishes an RRC connection with a cell on the second frequency layer in response to detecting the request. In such embodiments, the request can be generated by one of: an application running on the device and an operating system of the device.

[0144] In some embodiments, maintaining the second frequency layer in parallel includes monitoring both the first and second frequency layers and evaluating the first and second frequency layers for cell reselection. In certain embodiments, maintaining the second frequency layer in parallel includes performing a virtual reselection for the second frequency layer.

[0145] A first method for performing cell selection / reselection on a radio carrier frequency associated with a network slice is disclosed herein in accordance with embodiments of the disclosure. The first method can be performed by a user equipment device in a mobile communication network, such as the remote units 105, UE 205, and / or user equipment apparatus 400 described above. The first method includes configuring the UE to use a first set of network slices and a second set of network slices and camp on a first frequency layer of a RAN while in an RRC idle state, the first frequency layer supporting the first set of network slices, wherein the first set of network slices is prioritized for use with the first frequency. The first method includes iteratively performing a cell search on a second frequency layer while the UE is camped on the first frequency layer, the second frequency layer supporting the second set of network slices, wherein the second set of network slices is prioritized for use with the second frequency. The first method includes maintaining the second frequency layer in parallel while in the RRC idle state by performing a cell reselection on the second frequency.

[0146] In some embodiments, the first set of network slices is associated with a first group of applications and the second set of network slices is associated with a second group of applications. In certain embodiments, the first frequency layer comprises a set of one or more first cells (or cell sectors) in the RAN operating on the first frequency. In certain embodiments, the second frequency layer comprises a set of one or more second cells (or cell sectors) in the RAN operating on the second frequency. As described above, the first set of network slices is prioritized for use with the first frequency and the second set of network slices is prioritized for use with the second frequency.

[0147] In some embodiments, iteratively performing a cell search on the second frequency layer while the UE is camped on the first frequency layer includes performing detection, measurement, and evaluation of cells on the second frequency layer with reduced performance as compared to detection, measurement, and evaluation of cells on the first frequency layer. In one embodiment, performing the above operations with reduced performance means performing at longer intervals. In another embodiment, performing the above operations with reduced performance means skipping one or more iteration steps of evaluation.

[0148] In some embodiments, the first method further includes determining an interval for the UE to perform a cell search on the second frequency layer while the UE is camped on the first frequency layer, the interval determined based on a battery level of the UE or based on a power consumption level of the UE. In some embodiments, the first method further includes camping on the second frequency layer, instead of the first frequency layer, in response to a mobility level of the UE being below a predefined mobility threshold.

[0149] In some embodiments, the first method further includes determining that the second frequency layer has a higher priority than other frequency layers of the RAN and performing a cell search on the second frequency layer at an interval shorter than a search interval associated with a lower priority frequency layer of the RAN. In such embodiments, the first method can also include excluding frequency layers not associated with a preferred slice from consideration for inter-frequency reselection.

[0150] In some embodiments, the first method further includes determining that the second frequency has a lower priority based on a dedicated priority of the second frequency or based on a common priority of the second frequency. In such embodiments, the first method includes performing inter-frequency reselection for the second frequency even when a quality level of the first frequency satisfies a quality threshold.

[0151] In some embodiments, the first method further includes maintaining a prioritized table mapping network slices to corresponding frequencies and initiating a frequency scan for the second frequency at the UE while camped on the first frequency layer. In certain embodiments, a NAS layer entity in the UE informs an AS layer entity in the UE to search for a particular combination of a frequency and a network slice, the combination corresponding to a preferred network slice.

[0152] In some embodiments, the first method further includes detecting a request to establish a data connection with a network slice of the second set of network slices and establishing an RRC connection with a cell on the second frequency layer in response to detecting the request. In such embodiments, the request is generated by one of: an application running on the UE and an operating system of the UE.

[0153] In some embodiments, maintaining the second frequency layer in parallel includes monitoring both the first and second frequency layers and evaluating the first and second frequency layers for cell reselection. In certain embodiments, maintaining the second frequency layer in parallel includes performing a virtual reselection for the second frequency layer.

[0154] Disclosed herein is a second device for cell reselection using a persistence check value according to embodiments of the present disclosure. The second device can be implemented by a user equipment device in a mobile communication network, such as the remote unit 105, UE 205, and / or user equipment apparatus 400 as described above. The second device includes a processor and a transceiver that receives a broadcast message including a persistence check value for a cell. The processor generates a random value during a cell reselection procedure, compares the generated random value to the persistence check value, and selectively stops cell reselection based on a result of the comparison.

[0155] In some embodiments, selectively stopping cell reselection based on the result of the comparison includes continuing cell reselection in response to the generated random value being less than the received persistence check value. In response to the generated random value not being less than the received persistence check value, the processor stops cell reselection.

[0156] In some embodiments, the persistence check value is selected based on an RRC idle state UE load of the first cell. In some embodiments, the persistence check value is configured by the mobile communication network using RRC signaling.

[0157] Disclosed herein is a second method for cell reselection using a persistence check value according to embodiments of the present disclosure. The second method can be performed by a user equipment device in a mobile communication network, such as the remote unit 105, UE 205, and / or user equipment apparatus 400 as described above. The second method includes receiving a broadcast message including a persistence check value for a first cell and generating a random value during a cell reselection procedure. The second method includes comparing the generated random value to the persistence check value and selectively stopping cell reselection based on a result of the comparison.

[0158] In some embodiments, selectively stopping cell reselection based on the result of the comparison includes continuing cell reselection in response to the generated random value being less than the received persistence check value. In response to the generated random value not being less than the received persistence check value, the second method includes stopping cell reselection.

[0159] In some embodiments, the persistence check value is selected based on an RRC idle state UE load of the first cell. In some embodiments, the persistence check value is configured by the mobile communication network using RRC signaling.

[0160] Embodiments can be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the application is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A method of a user equipment ("UE") device in a mobile communication network, the method comprising: receiving a configuration of a first set of network slices and a second set of network slices; camping on a first frequency layer of a radio access network ("RAN") while in a radio resource control ("RRC") idle state, wherein the first frequency layer supports the first set of network slices, wherein the first set of network slices is prioritized for use with a first frequency; iteratively performing cell search on a second frequency layer while the UE camps on the first frequency layer, the second frequency layer supporting the second set of network slices, wherein the second set of network slices is prioritized for use with a second frequency; and concurrently maintaining the second frequency layer while in the RRC idle state by performing cell reselection on the second frequency.

2. The method of claim 1, wherein the first set of network slices is associated with a first group of applications and the second set of network slices is associated with a second group of applications.

3. The method of claim 1, wherein iteratively performing cell search on the second frequency layer while the UE camps on the first frequency layer comprises performing detection, measurement, and evaluation of cells on the second frequency layer with reduced performance compared to detection, measurement, and evaluation of cells on the first frequency layer.

4. The method of claim 1, further comprising determining an interval for the UE to perform cell search on the second frequency layer while the UE camps on the first frequency layer, the interval determined based on a battery level of the UE, a power consumption level of the UE, or a combination thereof.

5. The method of claim 1, further comprising: determining that the second frequency layer has a higher priority than other frequency layers of the RAN; and performing an optimized cell search on the second frequency layer by using an interval that is shorter than a search interval associated with the other frequency layers of the RAN.

6. The method of claim 5, further comprising excluding frequency layers not associated with a preferred slice from inter-frequency reselection regardless.

7. The method of claim 1, further comprising: determining that the second frequency has a lower priority based on one of: a dedicated priority of the second frequency or a common priority of the second frequency; and performing inter-frequency reselection for the second frequency even when a quality level of the first frequency meets a quality threshold.

8. The method of claim 1, further comprising: maintaining a prioritized table that maps network slices to corresponding frequencies; and initiating a frequency scan for the second frequency at the UE while camping on the first frequency layer.

9. The method of claim 8, wherein a non-access stratum ("NAS") layer entity in the UE informs an access stratum ("AS") layer entity in the UE to search for a particular combination of a frequency and a network slice, the combination corresponding to a preferred network slice.

10. The method of claim 1, further comprising: detecting a request to establish a data connection with a network slice of the second set of network slices; and establishing an RRC connection with a cell on the second frequency layer in response to detecting the request, wherein the request is generated by an application running on the UE, an operating system of the UE, or a combination thereof.

11. The method of claim 1, wherein maintaining the second frequency layer in parallel comprises monitoring and evaluating both the first and second frequency layers for cell reselection.

12. The method of claim 11, wherein maintaining the second frequency layer in parallel comprises performing a virtual reselection for the second frequency layer.

13. A user equipment (“UE”) device in a mobile communication network, the device comprising: a transceiver that camps on a first frequency layer of a radio access network (“RAN”) while in a radio resource control (“RRC”) idle state, wherein the first frequency layer supports a first set of network slices, wherein the first set of network slices is prioritized for use with a first frequency; and a processor that: iteratively performs cell search on a second frequency layer while the device camps on the first frequency layer, the second frequency layer supporting a second set of network slices, wherein the second set of network slices is prioritized for use with a second frequency, wherein the device is configured to use the first set of network slices and the second set of network slices; and maintains the second frequency layer in parallel while in the RRC idle state by performing cell reselection on the second frequency.

14. The device of claim 13, wherein the first set of network slices is associated with a first group of applications and the second set of network slices is associated with a second group of applications.

15. The device of claim 13, wherein the processor iteratively performs cell search on the second frequency layer while the device camps on the first frequency layer by performing detection, measurement, and evaluation of cells on the second frequency layer with reduced performance compared to detection, measurement, and evaluation of cells on the first frequency layer.

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